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Re: [CQ-Contest] Contesting and the FT8 Revolution

To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] Contesting and the FT8 Revolution
From: Jeff Clarke <ku8e@ku8e.com>
Date: Sat, 3 Jul 2021 15:55:55 -0400
List-post: <mailto:cq-contest@contesting.com>
Don,

You're exactly right about FT4. Joe probably wrote that code after he hooked up with some contesters (YCCC guys) who wanted to have a faster way to make FT8 contacts during digital contests. That being said there are very few stations that use FT4 during contests as most contacts are still being made on FT8. The reason for that is a good majority of FT8 contacts you make during a contest aren't with contesters. You can still work stations for contest credit even though they aren't in the contest. You aren't going to find that to be true on the FT4 frequencies during a digital contest.

You are 100% right about FT8 being a great propagation tool.  I did watch CT1BOH's presentation on YouTube. In a VHF contest on 6 meters I always know it's time to go to SSB or CW when the dB of the stations I'm hearing are above zero.

Jeff

On 7/3/2021 02:34 PM, Don Field wrote:
With respect Jeff, that's simply not true. From the WSJT site:



*The FT4 Protocol for Digital Contesting*





* FT4 is an experimental digital mode designed specifically for
radiocontesting. Like FT8, it uses fixed-length transmissions, structured
messages withformats optimized for minimal QSOs, and strong forward error
correction. T/Rsequences are 6 seconds long, so FT4 is 2.5 × faster than
FT8 and about the samespeed as RTTY for radio contesting. FT4 can work with
signals 10 dB weaker thanneeded for RTTY, while using much less bandwidth*

FT8 is a different matter, developed for weak signal work, primarily on the
6m band,

But Jose explained clearly in his original post why he thought there was
benefit to be gained from studying propagation, etc. by way of FT8.
Unfortunately the discussion has gone some way off the subject!

Regards

Don G3XTT





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On Sat, 3 Jul 2021 at 18:12, Jeff Clarke <ku8e@ku8e.com> wrote:

Again for the umpteenth time... Why are people talking about this
subject on a CONTESTING reflector? Neither FT8 or FT4 are contesting
modes. I guess this is more proof that FT8 has totally taken over ham
radio? I guess people are really bored and can't help themselves? Hello
Mr Moderator can you please tell people to stop!

Jeff

On 7/2/2021 09:01 PM, David Gilbert wrote:
I've gone through this stuff in detail with someone who knows far more
about digital signal processing than either of us, and everything I
said is possible with the exception that I will acknowledge that
synchronous operation has advantages.  My postulation does NOT involve
adhering to the FT8 or FT4 protocol as you seem to suggest below.  I
proposed a mode similar to FT4 except wider bandwidth (which dose NOT
necessarily degrade S/N as you claim) and a different set of other
parameters ... plus conversion to CW instead of fixed text blocks
simply to make it more adaptable to common contesting practice.

I don't care what you say ... it can be done, but it's going to take
somebody to work it up from scratch instead of trying to port FT8 or
FT4 to a different user interface.  Just about everything you said
below is wrong simply because you're stuck in that mental trap.

I will say again since nobody seems to get it ... FT8 and FT4 as
implemented by WSJT-X are not some new invention that locks all other
similar efforts into the same set of boundary conditions that K1JT
chose.  K1JT made very clever use of modern signal processing to
create FT8, FT4, and other similar modes but he chose a VERY
restrictive set of boundary conditions in order to implement his own
particular vision.  Those same modern signal processing techniques
could be implemented with different boundary conditions to give ham
radio (and in particular contesting) a much cleaner and more usable
interface.  Go read K1JT's descriptions of what he did and what
techniques he used, and if you then do a bit of searching you will
find lots of technical discussions of those same methods applied in
different ways to other tasks.  WSJT-X is unique, but the the science
behind it is not.

I know that I am flogging a dead horse here, but it frustrates the
hell out of me to see the opportunity that is being squandered simply
because the guy that came up with the first popular manifestation of
modern signal processing had such a limited vision of what it should be.

Dave   AB7E



On 7/2/2021 10:39 AM, Bill Coleman wrote:
On Jun 21, 2021, at 2:59 PM, David Gilbert <ab7echo@gmail.com> wrote:

Everything you just said there is the fault of WSJT-X as a user
interface ... not FT8 or FT4 as a mode.  They are NOT the same
thing.  WSJT-X is simply the narrow and restrictive vehicle by which
we have been exposed to the exceptional weak signal capability of
modern digital processing (forward error correcting, Costas array
processing, etc).  We'd all be having a LOT more fun with a more
open ended interface ... possibly with these parameters:

1.  wider individual signal bandwidth, such as maybe 200 Hz instead
of 83 Hz.
A wider bandwidth would potentially decrease the sensitivity of the mod

2.  fully tunable over the typical digital sub band (like RTTY does)
There’s absolutely nothing stopping you from running FT8 or FT4
anywhere in the digital sub-bands. You may not have many QSOs there,
but it is possible.

3.  Asynchronous in time ... i.e., not locked to a discrete and
specific clock window
This requirement is fundamentally incompatible to the way that FT8 or
FT4 work. The fixed transmission / reception windows are clearly a
part of the mode.

4.  shorter blocks of data with continuous feed of the blocks
Shorter blocks? The blocks today only convey 77 bits (BITS!) of
information. That’s right, it takes nominally 15 (or 7.5) seconds to
transmit 77 bits (BITS!) of information.

And continuous blocks don’t work either.

5.  sent via text blocks on the transmit end ... exactly as DVRs and
contest loggers do now
Remember the 77 bits (BITS!) mentioned earlier? Each transmitted
block has a certain structure, and typically contains the two
callsigns (caller and callee) and a little bit of additional text.
There’s no much room for sending any random text, because there’s
only a few bits available to on each sent block.

6.  displayed as text or converted to audible CW (or even digital
voice) on the receive end
Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
              -- Wilbur Wright, 1901

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